This invention relates generally to medical instruments and, more particularly, to a catheter handle for controlling the advancement of a guide wire through a body or a portion of the body, such as a blood vessel.
Guide wires are used during various interventional medical procedures to navigate therapeutic devices to a treatment site within a body, such as within a blood vessel. For example, to use a PTCA balloon device to clear an obstruction from a coronary artery, a guide wire is inserted into the femoral artery and advanced through the aorta to the obstruction in the coronary artery. The PTCA balloon device is then introduced over the wire and guided by the guide wire to the obstruction, where the balloon is then used to clear the obstruction.
However, advancing and steering guide wires through blood vessels is a difficult and risky procedure, even when practiced by skilled operators. Vessels are often tortuous or obstructed, or the tip of the guide wire itself is difficult to control. Thus, the use of guide wires typically entails the risk of puncturing or damaging the blood vessel, or else the guide wire simply fails because it is not rigid enough to penetrate certain barriers such as arterial plaque. A total occlusion of a blood vessel is an especially challenging barrier to successful use of a guide wire. Often, such occlusions are hardened by calcification and thus especially difficult to penetrate with a guide wire. When the tip of a guide wire is forced against such a hardened occlusion, the tip may be deflected toward the blood vessel wall, and, if advanced, may perforate the wall. To avoid such an undesirable outcome, the guide wire must be manually advanced by a skilled operator in carefully controlled increments. However, this is a difficult skill to acquire and even the most highly skilled operators risk damaging vessel walls. In addition, some calcified lesions present impenetrable barriers to the guide wire, even when operated by the most highly skilled operators.
Known guide wires include wires which range in diameter from 0.010 inches to 0.050 inches, and range in length from 2 feet to 10 feet. The distal tip of a typical known guide wire is shapeable into a curved or bent configuration and steered by turning the wire at the proximal end, thus transmitting torque through the wire to the distal tip. Known wires have varying degrees of rigidity (stiffness) which are selected according to the requirements of the particular procedure being performed. Softer, floppier wires are less likely to perforate vessel walls and are therefore better for navigating through tortuous arteries, but softer wires do not readily penetrate and cross occlusions. Stiffer wires are better for penetrating occlusions, but carry a greater risk of perforating or damaging vessel walls. Thus, an operator must trade off stiffness against a higher risk of perforation.
Other known guiding devices include catheters having a lumen for accommodating the movement of a guide wire. Such catheters are usually used in combination with a therapeutic device such as a PTCA balloon catheter. Known catheters also include exchange catheters, such as the Buchbinder catheter, which hold a position in the body while a wire extending through the catheter lumen is removed and replaced with a different wire. However, such catheters do not provide incremental control of guide wire advancement to minimize risk of damage.
It would therefore be desirable to provide a catheter handle for controlling the advancement of a guide wire through a catheter. It would also be desirable to provide such a catheter handle that reversibly couples with the catheter, so that the catheter handle can be removed from the catheter and coupled to another catheter. It would be further desirable to provide such a catheter handle that is adaptable for coupling with many types of catheters. It would be still further desirable to provide such a catheter handle with a braking mechanism for preventing undesired advancement of the guide wire.
These and other objects are attained by a catheter handle for controlling the advancement of a guide wire through a catheter. In an exemplary embodiment, the catheter handle has a proximal end and a distal end, and includes an advancement mechanism for controlling the advancement of a guide wire. The distal end of the catheter handle has a luer lock fitting so that the catheter handle is reversibly attachable to most known catheters. The proximal end of the catheter handle includes a retractable control knob coupled to the advancement mechanism for manual operation of the advancement mechanism.
In one embodiment, the catheter handle includes a housing having a distal end and a proximal end. A rotating flush port is coupled to the housing distal end, and a luer lock element, for example a female luer lock element, is coupled to the flush port. At the housing proximal end, the control knob is coupled to the guide wire advancement mechanism. More specifically, the control knob is slidably engaged with a control cylinder or sleeve within the handle housing. The advancement mechanism is positioned within the control cylinder or sleeve, and includes a spring assembly. The spring assembly is configured to reversibly apply friction to the guide wire.
The spring assembly includes a spring assembly block having an opening therethrough, and a guide wire guiding channel therethrough. The guide wire guiding channel and spring assembly block opening are continuous with one another. A friction wheel engages the opening through the spring assembly block. Thus, a guide wire passing through the guide wire guiding channel makes contact with the friction wheel.
At least one geared drive wheel is coupled to the friction wheel and is rotatably coupled to the spring assembly block. In one embodiment, the geared drive wheel includes a first geared drive wheel and a second geared drive wheel of the same diameter. A first spring element is coupled to a proximal wall of the control cylinder and bows outwardly to reversibly contact the control knob. A first ratchet element is coupled to the first spring element and reversibly engages a tooth on the geared drive wheel. A second spring element extends from the control cylinder proximal wall and contacts the spring assembly block. Opposite the contact of the second spring element with the spring assembly block, the spring assembly block includes an angled pedestal. The angled pedestal reversibly engages an indentation or groove on the inner surface of the control knob. A second ratchet element extends from the control cylinder proximal wall and reversibly engages a tooth on the geared drive wheel.
In use, the control knob has a first braking position in which the spring assembly holds friction wheel in contact with the guide wire and prevents movement of the guide wire. To advance the guide wire forward in precise incremental steps, manual pressure is briefly applied to the control knob by xe2x80x9cclickingxe2x80x9d the knob toward the handle housing, against the force produced by the first spring element, and then releasing the control knob. The brief pressure against the first spring element causes the first ratchet element to push against the engaged tooth of the first geared wheel and to slide behind the next. A brief counterclockwise rotation of the friction wheel results. The guide wire thus is briefly urged forward. The second ratchet element in engagement with the geared drive wheel acts as a locking element against further, undesired rotation of the friction wheel. The amount of rotation of the friction wheel and thus the corresponding forward motion of the guide wire is limited by the time it takes for first ratchet element and the second ratchet element to engage the next tooth on the geared drive wheel. Thus, the guide wire is moved forward in incremental steps controlled by the engagement of the geared drive wheel by the ratchet elements.
Since the geared drive wheel has a larger diameter than the friction wheel, the actual forward movement of the guide wire is reduced by the ratio of the friction wheel diameter to the drive wheel diameter, relative to the actual forward movement of knob. The incremental rotation of the geared drive wheel, and hence the incremental advancement of the guide wire, is adjustable by altering the diameter ratio of the friction wheel to the geared drive wheel, or by altering the number of teeth on the drive wheel. In one embodiment the incremental steps are about 0.5 mm.